The Canadian government is no longer using evidence gained from CIA interrogations of a top Al Qaeda detainee who was waterboarded.

According to documents obtained by NEWSWEEK, the Canadian Security Intelligence Service (CSIS), the country's national-security agency, last month quietly withdrew statements by alleged Al Qaeda leader Abu Zubaydah from public papers outlining the case against two alleged terror "sleeper" operatives in Ottawa and Montreal.

The move, which so far has received no public attention, is the latest sign of potential international fallout from the CIA's recent confirmation that it waterboarded a handful of high-profile Al Qaeda suspects in 2002 and 2003. The use of waterboarding and other harsh interrogation techniques were approved by the Bush White House and Justice Department. Waterboarding, which critics charge is a form of torture, involves strapping a suspect to an inclined board and forcing water into his lungs, typically by pouring water through a cloth placed over his nose and mouth.

The Canadian cases involve two men: Mohammed Harkat, an Algerian native living in Ottawa, and Moroccan-born Adil Charkaoui of Montreal. Both were arrested after the September 11 terror attacks and detained without charges on suspicions of links to Al Qaeda. Unable to develop enough evidence to bring criminal charges against either man, the CSIS sought to deport them on grounds that they had both allegedly spent time in Al Qaeda training camps in Afghanistan in the 1990s. (Both men now have been released on bail but remain under government scrutiny).

At least part of the case against the Canadian suspects was derived from the CIA-supplied statements of Zubaydah, the suspected Al Qaeda logistics chief who was arrested in Pakistan in 2002 and became the first high-value detainee subjected to waterboarding. A Canadian government dossier filed with the courts after Harkat's arrest, for example, stated that "a foreign agency" (an apparent reference to the CIA) "advised the Service [CSIS] in March 2003 that Abu Zubaida [sic] was able to identify the respondent [Harkat] by his physical description, including that he operated a guest house in Peshawar, Pakistan in the mid 1990s for mujahadeen travelling to Chechnya."

But last month, the CSIS filed a revised version of the dossier on Harkat as part of its case to deport the suspect. The new version deleted the detailed information from "the foreign agency" about Abu Zubaydah's identification of Harkat. Instead, in the new dossier, dated Feb. 22, 2008, the CSIS said simply that, "Based on its investigation, the Service concludes that HARKAT [sic] has associated with Abu Zubaydah [sic], one of [Osama] bin Laden's top lieutenants since the early 1990s." A footnote in the dossier attributes this information to news articles from the British press and to a counter terrorism newsletter published by a Chicago think tank.

Lawyer Paul Copeland, who represents Harkat, also provided NEWSWEEK with a letter sent to him in January by John Sims, Canada's deputy Justice minister, in which the government official said he could "confirm that [in Harkat's case] the Minister of Public Safety and the Minister of Citizenship and Immigration will not rely on information provided by Mr. Zubaida [sic]." Copeland also noted that similar allegations were deleted from an official CSIS report on Adil Charkaoui.

Copeland said the Canadian government's decision to drop claims about Harkat and Charkaoui that came from the CIA's interrogations of Abu Zubaydah indicates "the government of Canada, or at least the Canadian Security Intelligence Service, has concluded that everything that came from Abu Zubaydah was obtained by torture or cruel, inhuman or degrading treatment."

Asked why the statements from Zubaydah had been dropped from the dossiers against Harkat and Charkaoui, Bernard Beckhoff, a spokesman for Canada's public safety ministry, which oversees CSIS, said he could not comment on developments in either case because they are both still before the courts. But he then added, pointedly: "The CSIS director has stated publicly that torture is morally repugnant and not particularly reliable. CSIS does not knowingly use information which has been obtained through torture."

The CIA declined to comment on the CSIS's apparent rejection of the agency's evidence. Spokesman Paul Gimigliano told NEWSWEEK, "The agency's terrorist-detention program has been run in keeping with U.S. law. The Department of Justice deemed CIA's interrogation methods to be lawful at the time of their use."

But the development was immediately seized on by human-rights advocates as proof that the Bush administration's use of interrogation techniques rejected by the rest of the world will undermine counterterrorism cases in foreign courts. "This shows how the United States is shooting itself in the foot in terrorism cases," said John Sifton, the director of One World Research, a public-interest group that investigates human-rights abuses internationally.

The Canadian action comes as controversy within the United States over waterboarding and other "aggressive" interrogation methods is escalating. At a Capitol Hill hearing last month, CIA Director Gen. Michael Hayden acknowledged for the first time that the CIA had used waterboarding on three Al Qaeda detainees: Zubaydah, Khalid Sheikh Mohammed (the alleged mastermind of the 9/11 attacks) and Abd al-Rahim al-Nashiri (allegedly Al Qaeda's operations chief in the Persian Gulf). American and other intelligence agencies say that Zubaydah, a longtime bin Laden lieutenant of Palestinian origin, was in charge of pre-9/11 Al Qaeda training camps and guest houses in Pakistan and Afghanistan.

All three of the waterboarded suspects were held for years by the CIA in a still-secret network of clandestine detention centers. In September 2006, President Bush ordered them and about a dozen other CIA detainees transferred to the Guantánamo detention camp. The Defense Department recently charged Khalid Sheikh Mohammed and five other men with plotting the 9/11 plot in a case that will be tried under specially set up U.S. military tribunals. The cases, for which the suspects will face the death penalty, are expected to raise a host of complex legal issues about whether the men had been subjected to mistreatment by U.S. officials. (The Justice Department recently launched a criminal investigation into reports that CIA officials destroyed videotapes of interrogations of Zubayadah and Nashiri.)

The White House and Capitol Hill continue to be at odds over the issue: Congress recently approved an intelligence authorization bill that would expressly forbid the CIA from using waterboarding and certain other interrogation methods. Although it says the U.S. government no longer engages in waterboarding, the White House has signaled President Bush will veto the measure because he does not want to tie the agency's hands in the future.